This paper presents a PVT (process, voltage, temperature) compensated CMOS resistor to frequency read-out circuit for resistive sensing applications. Resistive sensing is used in different applications such as olfactory sensing. An accurate read-out circuit is needed to detect the resistance values for on-chip sensor arrays. Existing techniques suffer from PVT variations and require a large silicon chip area. The proposed design offers a simple, accurate, PVT insensitive sensor read-out circuit where a closed-loop configuration, a switched capacitor resistor, operational amplifier integrator, and a voltage-controlled oscillator are used. The design is implemented and fabricated using TSMC 180nm CMOS technology. The value of for the measured sensor’s resistance ranges between 10k and 100M ohms with accuracy of 0.1% while the chip area is 0.0455mm^2 with 189uW power consumption.